Nitrogen must be used for charging the accumulator. It is strictly forbidden to replace it with other gases. Before filling nitrogen, the remaining air in the ultrafine vertical mill shall be removed. Otherwise, the mixture of air and nitrogen will easily cause the burst of ling. According to relevant standards, the general inflation pressure is controlled in 60% - 70% of the system working pressure.During normal production, it is required to check nitrogen of accumulator once a week. When the vertical mill is inflated, the ling expands at the upper part with large diameter and thin wall, then expands to the lower part, pushes the ling outward to the side wall of the shell, and the vertical mill is filled with the whole container, and the friction between the outer wall of the ling and the inner wall of the shell is large.Therefore, during installation, the hydraulic oil shall be applied to the outer wall and inner wall of the shell of the ling to reduce the friction between the ling and the inner wall of the shell, and protect the ling. Before removing the accumulator, the pressure oil in the accumulator must be removed, and then the nitrogen in the leather bag can be released by the filling tool before the other parts can be removed.